This program is designed to evaluate the potential for environmental chemicals to adversely affect health due to exposures that occur during the perinatal period including fetal and juvenile exposure. Rats are exposed to environmental chemicals in utero during fetal development and exposures continue after birth and into adulthood. Endpoints evaluated include pregnancy status, maternal and fetal body weights, evaluations for birth defects, growth of offspring, timing of puberty, evaluations for birth defects, evaluations for infertility and reproductive problems, and organ toxicity, especially as it relates to reproductive organs including ovary, uterus, testes and epididymides. The contract evaluates toxicity of selected chemicals in rats and mice using dietary, gavage, or drinking water administration. The contract includes performing prestart chemistry activities, ranging finding studies and multi-generation reproductive toxicity studies including modified one-generation studies in laboratory animals.